waste characterization methods
DESCRIPTION
WASTE CHARACTERIZATION METHODS. S. Vanderperre Belgatom. Vanderperre, Belgatom, chapter 7. WASTE CHARACTERIZATION METHODS. 1. Measurement methods 2. Predictive calculation models. Table of contents. Introduction LLWAA Code (Low Level Waste Activity Assessment) LLWAA-DECOM Code - PowerPoint PPT PresentationTRANSCRIPT
1
WASTE CHARACTERIZATION METHODSS. Vanderperre
Belgatom
Vanderperre, Belgatom, chapter 7
2
WASTE CHARACTERIZATIONMETHODS
1. Measurement methods
2. Predictive calculation models
3
Table of contents
• Introduction• LLWAA Code
(Low Level Waste Activity Assessment)
• LLWAA-DECOM Code
• Conclusions
4
Introduction
• Typical approaches used in most EU countries to determine critical nuclide inventories of waste packagessimplified calculation based on engineering judgment and extrapolation of international experience
selection of ratios between key nuclides and a critical nuclide, from experimental databases
use of predictive calculation codes taking into account the plant’s characteristics and operating conditions
5
LLWAA Code (Low Level Waste Activity Assessment)
• Calculation of radionuclides inventories in process and technological NPP waste on the basis of characteristics and operating conditions of the NPP
• Prediction of inventories of isotopes that are difficult to measure by routine techniques in NPP waste streams
• Basis for the definition of a radiological source term for surface or near-surface repository long-term risk assessment
6
List of radionuclides taken into account by LLWAA
Activation Products 14C 36Cl 58Co 60Co 55Fe 59Ni 63Ni 94Nb 3H
Fission Products
90Sr 99Tc 129I 134Cs 135Cs 137Cs 234U 235U 237Np
238U 238Pu 239Pu 240Pu 241Pu 242Pu 241Am 243Am 244Cm
7
Activities in Reactor Coolant System and in Nuclear Auxiliary SystemsActivities in Reactor Coolant System and in Nuclear Auxiliary Systems
Core activities inventories
Measured I-131, I-133, I-134, Cs-134 and Cs-137
activities in the RCS
Corrosion rates of in-core and out-of-core equipment in contact
with the primary coolant
water and chemicaladditive activation
products H-3, C-14, Cl-36
Cs-137 cladding defects and recoil
FP, TRU-recoil FP, TRU claddingdefects
Activation of corrosionproducts
ActivitiesActivities build-upbuild-up andand inventoriesinventories ininOn site conditioned waste Non-conditioned waste
Scaling factors
LLWAA general structure
Water and chemicaladditive activation
productsH-3, C-14 and Cl-36
8
LLWAA category 1 parameters
• Parameters adapted each year to produce specific annual outputs of the code60Co activity in the primary coolant (activation products)
137Cs activity in the primary coolant (fission products)
131I, 133I and 134I activities in the primary coolantChlorides concentration in the primary coolantNumber of refueling operation (0 or 1)
9
LLWAA input screen for category 1 parameters
10
LLWAA category 2 parameters
• Parameters that can vary according to NPP operating conditionsprimary-to-secondary leak rateprimary coolant purification ratesteam generator blowdown rateboron concentration at BOLboron concentration in non recycled waste evaporator
evaporator concentrates production
11
LLWAA modification screen with category 2 parameters
12
LLWAA category 3 parameters
• Design parameters of the code that are fixed and not accessible to the usercore activity inventoriescladding defects and diffusion coefficientsfraction of activity in soluble and in insoluble forms
decontamination factors of ion exchange resins and filters
equipment corrosion rates
13
LLWAA calculated activitiesof mixed spent IERs at Tihange NPP
in 2001 [MBq/m³]
3H 6.23E+01 60Co 5.74E+05 135Cs 2.64E-01 239Pu 9.52E-01
14C 2.04E+03 63Ni 2.05E+05 137Cs 6.14E+04 240Pu 1.34E+00
36Cl 2.56E+00 94Nb 5.72E+02 234U 3.83E-03 241Pu 3.31E+02
54Mn 2.53E+05 90Sr 8.38E+02 235U 1.04E-04 241Am 2.72E+00
55Fe 4.70E+05 99Tc 2.41E+01 237Np 8.01E-04 242Pu 4.76E-03
58Co 2.46E+06 129I 3.61E-01 238U 8.56E-04 243Am 2.97E-01
59Ni 1.76E+03 134Cs 6.73E+04 238Pu 7.63E+00 244Cm 7.25E+00
14
LLWAA validation
• Comparison of LLWAA predicted values with values derived from measurements performed by the Belgian Nuclear Research Centre (SCK CEN) on samples ofspent ion exchange resinsspent filters cartridgesevaporator concentrates
• On behalf of ONDRAF/NIRAS, in-depth critical review by AVN (Belgian Licensing Authority)
15
Inventoriesconditioned
waste packages
Inventories non conditioned waste packages
Combustiblewaste
Non-combustible waste
DECLDECL
LLWAALLWAA Calculated• specific activities
• scaling factors
Category1, 2 and 3
parameters
Measurements• gamma spectrometry
• contact dose rates
Deposited activities
scaling factors
LLWAA-DECOMLLWAA-DECOMInput• number of cycles, cycle length• particle properties• piping properties• thermal hydraulic conditions
Measurements• gamma spectrometry
Co-60, Cs-137• contact dose rates
Depositedactivities
inventories
LLWAA-ASHESLLWAA-ASHES
Scaling factors ashes Co-60, Cs-137spectrometricmeasurements
Inventoriesashes
LLWAA Code LLWAA Code ExtensionsExtensions
16
LLWAA-DECOM input parameters
• Contamination in the streams of the nuclear systems (calculated by LLWAA)
• Characteristics of the equipment to be dismantled (piping diameter, pipe rugosity …)
• Operating conditions in piping systems (fluid velocity, pH, temperature, number of cycles, cycle life …)
• Particulate diameter distribution of corrosion products
• Time elapsed between the reactor final shutdown and the decontamination or dismantling
17
LLWAA-DECOM input parameters
18
LLWAA-DECOM output
• Particle deposition and release rates• Deposited activities (Bq/m2) and scaling factors at any
given time (shutdown, decontamination or decommissioning)
19
LLWAA-DECOM output
20
LLWAA-DECOM validation
• Direct measurements of deposited activities present a number of practical difficulties and are not often available
• Coupling of a dose rate model to the calculated deposited activities and comparison between calculated and measured dose rate
• Good agreement between calculated and measured dose rates during NPP
shutdown and decontamination operations predicted and measured deposited activities during
steam generator replacement programmes
21
Conclusions
LLWAA and LLWAA-DECOM codes
are predictive calculation codes used for Belgian NPPs
allow significant savings in time, money and operator exposure
22
Conclusions
LLWAA and LLWAA-DECOM codes increase confidence in source terms for near-surface or geological repositories